i4bipr(4)

NAME

i4bipr - isdn4bsd IP over ISDN B-channel network driver

device "i4bipr" [count]

The i4bipr driver interfaces the IP subsystem of the operat
ing system with the isdn4bsd package so that transport of IP packets
over an ISDN link is possible.
The driver just packs IP packets without anything appended
or prepended into raw HDLC packets on the B channel and transfers them to
a remote site. IP packets received from the remote site are queued
into the local IP protocol stack.
The format of the resulting packet on the B channel is:: (HDLC opening flag) (IP-packet) (CRC) (HDLC closing; flag)
In the case where an IP packet for a remote site arrives in
the driver and no connection has been established yet, the driver com
municates with the isdnd(8) daemon to establish a connection.
The driver has support for interfacing to the bpf(4) subsys
tem for using
tcpdump(1) with the ipr interfaces.
The driver optionally (when compiled with the IPR_VJ option)
provides Van Jacobsen header compression, under control of the link0 and
link1 options to ifconfig(8):: link0 Apply VJ compression to outgoing; packets on this
interface, and assume that incoming

packets
require decompression.; link1 Check incoming packets for Van Jacob; sen compres
sion; if they appear to be com

pressed, automatically set link0.
The default values are on for link1 and off for link0.